Do not register only to promote your site with a link in profile!
This seems like a common spamming practice. Some people register only so that they can have one more link to their site, putting the URL of their homepage in a Nuxified profile. Such members never contribute anything and only inflate the number of users on the site while making it look not so good. This is considered spam and is therefore forbidden.
To those who do it or consider doing it, don't bother! Your account will be deleted. It is quite easy to detect suspicious profiles!